"Leetcode-Interview algorithm classic-java Implementation" "216-combination Sum III (combined number of sums)"

"216-combination Sum III (combined number of sums)" "leetcode-Interview algorithm classic-java Implementation" "All topics Directory Index" code Download "Https://github.com/Wang-Jun-Chao" Original Question

Find all possible combinations of k numbers this add up to a number n, given this only numbers from 1 to 9 can be used and Each combination should is a unique set of numbers.
Ensure that numbers within the set is sorted in ascending order.
Example 1:
Input:k = 3, n = 7
Output:
　　[[1,2,4]]
Example 2:
Input:k = 3, n = 9
Output:
　　[[1,2,6], [1,3,5], [2,3,4]]

Main Topic

Look for all combinations that satisfy the sum of K equals n, only the number 1-9 is allowed, and the numbers in each combination should be unique. Make sure the numbers in the group are in ascending order.

Thinking of solving problems

Backtracking method

Code Implementation

Algorithm implementation class

ImportJava.util.Collections;ImportJava.util.LinkedList;ImportJava.util.List; Public  class solution {     PublicList<list<integer>>combinationSum3(intKintN) {//For saving all resultslist<list<integer>> result =NewLinkedlist<> ();//For saving intermediate resultslist<integer> list =NewLinkedlist<> ();//Conditions are met on the problem solving operation        if(k >0&& k <=9) {Solve (k,1N0, list, result); }//Return results        returnResult }/** * Solution Method * * @param k number of elements per solution * @param cur currently processing k elements * @par     Am remainder K-cur + 1 elements and * @param Prevval The value of the cur-1 element * @param List of elements to be solved in the collection class * @param result save container for all results * /     Public void Solve(intKintCurintRemainder,intPrevval, list<integer> List, list<list<integer>> result) {//Process the last element        if(cur = = k) {//remainder is the value of the last solution element, it must be greater than the value of the previous solution element and cannot exceed 9            if(Remainder > Prevval && remainder <=9) {//Add element valueList.add (remainder);//Copy results to a new queueList<integer> one =NewLinkedlist<> (); for(Integer i:list)                {One.add (i); }//Save ResultsResult.add (one);//Delete the last element for site restoreList.remove (List.size ()-1); }        }//Not the last element        Else if(Cur < k) { for(inti = Prevval +1; I <=9-(K-cur); i++) {//Add elementList.add (i);//Recursive solutionSolve (k, cur +1, Remainder-i, I, list, result);//Field restoreList.remove (List.size ()-1); }        }    }}

Evaluation Results

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"Leetcode-Interview algorithm classic-java Implementation" "216-combination Sum III (combined number of sums)"